<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    .box {
      width: 1200px;
      height: 600px;
      display: grid;
      grid-template-columns: repeat(3, 1rf);
      grid-template-rows: repeat(4, 1rf);
      gap: 40px;
    }

    .box div {
      background-color: green;
    }

    .item1 {
      /* 表示第一条网格线开始到第二条结束 */
      grid-column: 1/2;
      grid-row: 1/2;
    }

    .item2 {
      grid-column: 2/4;
      grid-row: 1/3;
    }

    .item3 {
      grid-column: 1/2;
      grid-row: 2/5;
    }

    .item4 {
      grid-column: 3/4;
      grid-row: 3/4;
    }

    .item5 {
      grid-column: 2/3;
      grid-row: 3/5;
    }

    .item6 {
      grid-column: 3/4;
      grid-row: 4/5;
    }
  </style>
</head>

<body>
  <div class="box">
    <div class="item1">one</div>
    <div class="item2">two</div>
    <div class="item3">three</div>
    <div class="item4">four</div>
    <div class="item5">five</div>
    <div class="item6">six</div>
  </div>
</body>

</html>